Fielf of the Invention
The present invention relates to a process for using gas/solid reactions in which the solid reactant contains an at least partially hydrated salt.
The present invention more particularly relates to a process for using gas/solid chemical reactions which makes it possible to modify the position of the equilibrium line of the reaction under consideration in a Clapeyron diagram and to reduce its slope, in order to cover a wider temperature region for a fairly limited pressure range.
The process targeted by the invention is based on a reversible reaction between a solid and a gas of the type: ##STR1##
The reaction is exothermic in the 1 direction, which means that in this direction it gives off heat, and endothermic in the 2 direction, that is to say that in this direction it absorbs heat. As it is a true chemical reaction, there is a univariant system at equilibrium, that is to say that there exists a one-to-one relationship between the temperature and the pressure of the form log P=A-B/T, in which expression P is the pressure, T the temperature in .degree.K. and A and B are constants characteristic of the salt/gas pair used. Thus, the equilibrium of the solid/gas reaction in question is characterized by a straight line in a Clapeyron diagram. This straight line is known as the equilibrium line of the reaction.
The use of an anhydrous solid reactant is generally reflected by a high slope of the equilibrium line of the reaction in a Clapeyron diagram, which does not make it possible to cover a wide temperature region for a fairly limited pressure range. In particular, the covering of the LT and MT regions mentioned in FIG. 6 for a pressure range from a few mm Hg to several tens of bar is not easy in this scenario.